SOLUTION: Bob leaves the same time as Jane. Bob drives 4 Mi/h faster than Jane. After 2 hours of driving in opposite directions, they are 116 miles apart. How fast is Bob driving?

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons  -> Linear Equations Lesson -> SOLUTION: Bob leaves the same time as Jane. Bob drives 4 Mi/h faster than Jane. After 2 hours of driving in opposite directions, they are 116 miles apart. How fast is Bob driving?      Log On


   

Question 881332: Bob leaves the same time as Jane. Bob drives 4 Mi/h faster than Jane. After 2 hours of driving in opposite directions, they are 116 miles apart. How fast is Bob driving?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +s+ = Jane's speed in mi/hr
+s+%2B+4+ = Bob's speed in mi/hr
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For this problem, think of one of them
( either one ) as standing still and the other one
travelling at the sum of their speeds
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+116+=+%28+s+%2B+s+%2B+4+%29%2A2+
+4s+%2B+8+=+116+
+4s+=+108+
+s+=+27%0D%0A%7B%7B%7B+s+%2B+4+=+31+
Bob is driving 31 mi/hr
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check:
Jane's equation:
+d%5B1%5D+=+27%2A2+
+d%5B1%5D+=+54+ mi
and
Bob's equation:
+d%5B2%5D+=+31%2A2+
+d%5B2%5D+=+62+
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+d%5B1%5D+%2B+d%5B2%5D+=+54+%2B+62+
+d%5B1%5D+%2B+d%5B2%5D+=+116+ mi
OK